dioxus_rsx/
raw_expr.rs

1use proc_macro2::TokenStream as TokenStream2;
2use quote::ToTokens;
3use std::hash;
4use syn::{parse::Parse, spanned::Spanned, token::Brace, Expr};
5
6/// A raw expression potentially wrapped in curly braces that is parsed from the input stream.
7///
8/// If there are no braces, it tries to parse as an expression without partial expansion. If there
9/// are braces, it parses the contents as a `TokenStream2` and stores it as such.
10#[derive(Clone, Debug)]
11pub struct PartialExpr {
12    pub brace: Option<Brace>,
13    pub expr: TokenStream2,
14}
15
16impl Parse for PartialExpr {
17    fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
18        // Parse as an expression if there is no brace
19        if !input.peek(syn::token::Brace) {
20            let expr = input.parse::<syn::Expr>()?;
21            return Ok(Self {
22                brace: None,
23                expr: expr.to_token_stream(),
24            });
25        }
26
27        let content;
28        let brace = Some(syn::braced!(content in input));
29        let expr: TokenStream2 = content.parse()?;
30
31        Ok(Self { brace, expr })
32    }
33}
34
35impl ToTokens for PartialExpr {
36    fn to_tokens(&self, tokens: &mut TokenStream2) {
37        match &self.brace {
38            Some(brace) => brace.surround(tokens, |tokens| self.expr.to_tokens(tokens)),
39            _ => self.expr.to_tokens(tokens),
40        }
41    }
42}
43
44impl PartialExpr {
45    pub fn as_expr(&self) -> syn::Result<syn::Expr> {
46        // very important: make sure to include the brace in the span of the expr
47        // otherwise autofmt will freak out since it will use the inner span
48        if let Some(brace) = &self.brace {
49            let mut tokens = TokenStream2::new();
50            let f = |tokens: &mut TokenStream2| self.expr.to_tokens(tokens);
51            brace.surround(&mut tokens, f);
52            return syn::parse2(tokens);
53        }
54
55        let expr = self.expr.clone();
56        syn::parse2(expr.to_token_stream())
57    }
58
59    pub fn from_expr(expr: &Expr) -> Self {
60        Self {
61            brace: None,
62            expr: expr.to_token_stream(),
63        }
64    }
65    pub fn span(&self) -> proc_macro2::Span {
66        if let Some(brace) = &self.brace {
67            brace.span.span()
68        } else {
69            self.expr.span()
70        }
71    }
72}
73
74impl PartialEq for PartialExpr {
75    fn eq(&self, other: &Self) -> bool {
76        self.expr.to_string() == other.expr.to_string()
77    }
78}
79
80impl Eq for PartialExpr {}
81
82impl hash::Hash for PartialExpr {
83    fn hash<H: hash::Hasher>(&self, state: &mut H) {
84        self.expr.to_string().hash(state);
85    }
86}
dioxus_rsx/raw_expr.rs

dioxus_rsx/
raw_expr.rs
